1. Field of the Invention
The present invention relates to a heat exchanger with a leakage vent, and more particularly to a fully brazed heat exchanger having an arrangement preventing the two media inside the heat exchanger from mixing in case of leakage. The invention also allows quick detection of the leakage. A separation zone is provided at each connection to the heat exchanger. The separation zone comprises a blocked-off space with leakage vents, where any leakage can be detected.
2. Discussion of the Background
The fully brazed heat exchangers of today comprise of brazed packs of plates lacking any possibility of internal inspection. One problem existing in such heat exchangers is that a brazing at a connection may break inside the heat exchanger. An invisible leak is then created inside the heat exchanger, whereupon the media become mixed without this being detectable from outside the heat exchanger. This has meant that such heat exchangers have been used only reluctantly e.g. for the cooling of machinery where the oil lubricating the machine is cooled by heat exchange with water. Water mixing into the oil could cause catastrophic results for the machine, which could in the worst case seize up completely.
Another type of heat exchanger is the seal type heat exchanger, which is held together by screw joints, with seals between the heat exchanger plates. The above problem of internal leakage has in these heat exchangers been solved by means of the seal extending in such a manner as to create a separation zone at each connection, and to create a leakage vent in the seal at the edge of the heat exchanger, in the separation zones. This means that any leakage will be externally visible. However, the heat exchanger will also have a large number of holes at the sides, resulting in other practical problems. Furthermore, the seal type heat exchanger can only be used for lower pressures (up to 50 bar); whereas brazed heat exchangers can be used for considerably higher pressures (up to 300 bar). The heat exchanger seals will age and have to be replaced at regular intervals. Brazed heat exchangers on the other hand are practically maintenance-free and furthermore cheaper to produce than seal type heat exchangers. Thus, it would be highly desirable to be able to use fully brazed heat exchangers in more applications than has been previously possible.
The present invention solves the above problem of internal leakage in a fully brazed heat exchanger by providing a separation zone at the connections. In case of a brazed seam breaking, a leakage occurs into the separation zone. The separation zone has a leakage vent to the exterior surroundings, enabling quick detection of the leakage. However, no mixing of media occurs due to the leakage.